Jaw crusher units typically comprise a fixed jaw and a movable jaw that together define a crushing zone. A drive mechanism is operative to rock the movable jaw back and forth in order to crush material in the crushing zone.
The crushing zone is generally convergent towards its lower discharge end so that crushable material fed to the upper and wider end of the zone is capable of falling downward under gravity whilst being subject to repeated cycles of crushing movement in response to the cyclical motion of the movable jaw. The crushed material is then discharged under gravity through the lower and narrower discharge end onto a conveyor belt for onward processing or discharge from the crusher unit to a suitable stock pile.
Commonly, the frame that supports the fixed jaw is referred to as the front frame end. The moveable jaw is connected to what is typically referred to as a back frame end via a mechanically actuated link mechanism that serves to control and stabilise the oscillating movement of the jaw relative to the stationary jaw. Typically, the link mechanism is both statically and dynamically linearly adjustable to control the grade or size of the resultant crushed material, to facilitate absorption of the impact forces generated by the crushing action and to expand or open the crushing zone to prevent damage to the crusher in the event of non-crushable material being accidentally introduced into the crushing zone.
Example jaw crushers comprising linkage assemblies connecting the back frame and front frame end are described in FR 2683462; EP 0773067; WO 97/36683; U.S. Pat. No. 5,799,888; WO 02/34393; WO 2008/010072, JP 2009-297591 EP 0148780, JP 60-251941, U.S. Pat. No. 7,143,970, CN 2832296, U.S. Pat. No. 6,375,105 and US 2003/0132328.
Jaw crushers of the types identified above typically include a retraction or tension assembly mounted at a lower region of the moveable jaw that is operative to apply pressure on the various components of the moveable jaw linkage positioned between the jaw and the back frame end. Additionally, conventional jaw crushers typically comprise an adjusting unit that controls the distance between the jaws. Example units include a shim package, a wedge system or a hydraulic toggle. This is useful to selectively adjust the jaw separation distance to either accommodate larger rocks within the crushing zone or allow passage of uncrushable material to exit the crusher and avoid damage. In some cases, a retraction assembly is used to mechanically separate the jaws.
Conventionally, one end of the retraction assembly attaches to a lower region of the moveable jaw with the other end mounted at an underside region of the back frame end. In some instances, a coil spring extends longitudinally from a hydraulic ram to provide an additional mounting linkage between the cylinder and the crusher frame. The coil spring is typically operative to limit the motion/extension resultant from the cyclical crushing movement of the moving jaw. The hydraulic ram is configured for adjustment of the position of the moving jaw when the jaw separation setting (close side setting (CSS)) is changed by the adjustment unit.
However, conventional retraction assemblies that either allow adjustment of the CSS or enable shim-setting modes include relatively complicated retraction actuator and hydraulic jack arrangements that perform separate functions. The conventional systems typically comprise many components and moving parts which accordingly increase the frequency for maintenance and the need to replace worn parts. What is required is a jaw mounting assembly configured to provide a simple, efficient and reliable mechanism for adjustment of the CSS and/or shim-setting.